"""Database objects for storing Markov chains."""

import logging

from django.db import models

log = logging.getLogger(__name__)


class MarkovContext(models.Model):
    """Define contexts for Markov chains."""

    name = models.CharField(max_length=200, unique=True)

    def __str__(self):
        """String representation."""
        return "{0:s}".format(self.name)


class MarkovState(models.Model):
    """One element in a Markov chain, some text or something."""

    start1 = '__start1'
    start2 = '__start2'
    stop = '__stop'

    k1 = models.CharField(max_length=256)
    k2 = models.CharField(max_length=256)
    v = models.CharField(max_length=256)

    count = models.IntegerField(default=0)
    context = models.ForeignKey(MarkovContext, on_delete=models.CASCADE)

    class Meta:
        index_together = [
            ['context', 'k1', 'k2'],
            ['context', 'v'],
        ]
        unique_together = ('context', 'k1', 'k2', 'v')

    def __str__(self):
        """String representation."""
        return "{0:s},{1:s} -> {2:s} (count: {3:d})".format(self.k1, self.k2, self.v, self.count)